Role of CD97(stalk) and CD55 as molecular markers for prognosis and therapy of gastric carcinoma patients

Single cell profiling of γδ hepatosplenic T-cell lymphoma unravels tumor cell heterogeneity associated with disease progression

PURPOSE

Hepatosplenic T-cell lymphoma (HSTCL), mostly derived from γδ T cells, is a rare but very aggressive lymphoma with poor outcomes. In this study, we generated the first single cell landscape for this rare disease and characterized the molecular pathogenesis underlying the disease progression.

METHODS

We performed paired single cell RNA-seq and T cell receptor (TCR) sequencing on biopsies from a HSTCL patient pre- and post- chemotherapy treatments. Following by a series of bioinformatics analysis, we investigated the gene expression profile of γδ HSTCS as well as its tumor microenvironment (TME).

RESULTS

We characterized the unique gene expressing signatures of malignant γδ T cells with a set of marker genes were newly identified in HSTCL (AREG, PLEKHA5, VCAM1 etc.). Although the malignant γδ T cells were expanded from a single TCR clonotype, they evolved into two transcriptionally distinct tumor subtypes during the disease progression. The Tumor_1 subtype was dominant in pre-treatment samples with highly aggressive phenotypes. While the Tumor_2 had relative mild cancer hallmark signatures but expressed genes associated with tumor survival signal and drug resistance (IL32, TOX2, AIF1, AKAP12, CD38 etc.), and eventually became the main tumor subtype post-treatment. We further dissected the tumor microenvironment and discovered the dynamically rewiring cell-cell interaction networks during the treatment. The tumor cells had reduced communications with the microenvironment post-treatment.

CONCLUSIONS

Our study reveals heterogenous and dynamic tumor and microenvironment underlying pathogenesis of HSTCL and may contribute to identify novel targets for diagnosis and treatment of HSTCL in the future.

CD55 in cancer: Complementing functions in a non-canonical manner

CD55, or decay accelerating factor, is a membrane lipid microdomain-associated, GPI-anchored protein implicated in the shielding of cells from complement-mediated attack via accelerating decay of C3 and C5. Loss of CD55 is associated with a number of pathologies due to hyperactivation of the complement system. CD55 is also implicated in cancer progression thought to be driven via its role in cell shielding mechanisms. We now appreciate that CD55 can signal intracellularly to promote malignant transformation, cancer progression, cell survival, angiogenesis, and inhibition of apoptosis. Outside-in signaling via CD55 is mediated by signaling pathways including JNK, JAK/STAT, MAPK/NF-κB, and LCK. Moreover, CD55 is enriched in the cancer stem cell (CSC) niche of multiple tumors including breast, ovarian, cervical, and can be induced by chemotherapeutics and hypoxic environments. CSCs are implicated in tumor recurrence and chemoresistance. Here, we review the unexpected roles of CD55 in cancer including the roles of canonical and noncanonical pathways that CD55 orchestrates. We will highlight opportunities for therapeutic targeting CD55 and gaps in the field that require more in-depth mechanistic insights.

CD97 serves as a novel biomarker of immune cell infiltration in hepatocellular carcinoma

BACKGROUND

CD97 is the most widely expressed G protein-coupled receptor in the epidermal growth factor seven-span transmembrane family. It plays a vital role in cell adhesion, migration, and cell connection regulation. We explored the role of CD97 in hepatocellular carcinoma (HCC).

METHODS

We evaluated CD97 mRNA expression in HCC using TNMplot and the Gene Expression Omnibus database. The clinical prognostic significance of CD97 in HCC patients was evaluated by gene expression profiling interactive analysis, the Kaplan-Meier plotter, and the UALCAN database. The Tumor Immune Estimation Resource (TIMER) and CIBERSORT databases were used to analyze the relationships among CD97, genes positively related with CD97, and tumor-infiltrating immune cells.

RESULTS

CD97 was highly expressed in HCC tissues and was associated with an adverse prognosis. CD97 and genes positively related with CD97 were positively correlated with the abundance of tumor-infiltrating immune cells and strongly correlated with tumor-infiltrating macrophages (all r ≥ 0.513, P < 0.001). CD97 was positively correlated with M2 macrophage and tumor-associated macrophage markers (both r ≥ 0.464, P < 0.001). CD97 was found to be an immune-related gene in HCC and positively correlated with the TOX, PD-L1, PD-L2, CTLA4, and PD-1 immune checkpoint genes. CD97 copy number alterations affect the level of immune cell infiltration and mRNA expression.

CONCLUSIONS

CD97 can be used as a potential molecular marker of prognosis in HCC, which is associated with immune cell infiltration.

Integrative Analysis of Complement System to Prognosis and Immune Infiltrating in Colon Cancer and Gastric Cancer

Background

The complement system acts as an integral part of the innate immune response, which acts primarily to remove pathogens and injured cells. Emerging evidence has shown the activation of the immune regulatory function of complements in the tumor microenvironment (TME). We revealed the expression levels of various complements in human cancers and their role in tumor prognosis and immune infiltration.

Methods

The differential expression of complements was explored via the Tumor Immune Estimation Resource (TIMER) site and the Oncomine database. To investigate whether these differentially expressed complements have correlation with the prognosis of gastric cancer (GC) and colon cancer, their impact on survival was assessed using the PrognoScan database and Kaplan-Meier plotter. The correlations between complements and tumor immune-infiltrating levels and immune gene markers were statistically explored in TIMER based on Spearman's correlation coefficients and p-values.

Results

In two colon cancer cohorts, an increased expression level of DAF (CD55) has statistically significant correlation with poor disease-free survival (DFS). High C3, CR4, and C5aR1 expression levels were significantly related with poor prognosis in GC patients. In addition, C3, CR4, and C5aR1 expression was positively related to the tumor purity and infiltration levels of multiple immune cells in stomach adenocarcinoma (STAD). Moreover, the expression levels of C3, CR4, and C5aR1 were also strongly correlated with various immune marker sets, such as those of tumor-associated macrophages (TAMs), M1 and M2 macrophages, T cell exhaustion, Tregs, and DCs, in STAD. Additionally, CD55 has positive correlation with few immune cell infiltration levels in colon adenocarcinoma (COAD), but its correlation with immune marker sets was not statistically significant.

Conclusion

These findings confirm the relationship between various complements and tumor prognosis and immune infiltration in colon cancer and GC. CD55 may serve as an indicator on the survival prognosis of patients with colon cancer. Furthermore, as biomarkers for poor prognosis in GC, complements C3, CR4, and C5aR1 may provide potential biological targets for GC immunotherapy.

The Role of Membrane Bound Complement Regulatory Proteins in Tumor Development and Cancer Immunotherapy

It has long been understood that the control and surveillance of tumors within the body involves an intricate dance between the adaptive and innate immune systems. At the center of the interplay between the adaptive and innate immune response sits the complement system—an evolutionarily ancient response that aids in the destruction of microorganisms and damaged cells, including cancer cells. Membrane-bound complement regulatory proteins (mCRPs), such as CD46, CD55, and CD59, are expressed throughout the body in order to prevent over-activation of the complement system. These mCRPs act as a double-edged sword however, as they can also over-regulate the complement system to the extent that it is no longer effective at eliminating cancerous cells. Recent studies are now indicating that mCRPs may function as a biomarker of a malignant transformation in numerous cancer types, and further, are being shown to interfere with anti-tumor treatments. This highlights the critical roles that therapeutic blockade of mCRPs can play in cancer treatment. Furthermore, with the complement system having the ability to both directly and indirectly control adaptive T-cell responses, the use of a combinatorial approach of complement-related therapy along with other T-cell activating therapies becomes a logical approach to treatment. This review will highlight the biomarker-related role that mCRP expression may have in the classification of tumor phenotype and predicted response to different anti-cancer treatments in the context of an emerging understanding that complement activation within the Tumor Microenvironment (TME) is actually harmful for tumor control. We will discuss what is known about complement activation and mCRPs relating to cancer and immunotherapy, and will examine the potential for combinatorial approaches of anti-mCRP therapy with other anti-tumor therapies, especially checkpoint inhibitors such as anti PD-1 and PD-L1 monoclonal antibodies (mAbs). Overall, mCRPs play an essential role in the immune response to tumors, and understanding their role in the immune response, particularly in modulating currently used cancer therapeutics may lead to better clinical outcomes in patients with diverse cancer types.

Identification of ADGRE5 as discriminating MYC target between Burkitt lymphoma and diffuse large B-cell lymphoma

Background

MYC is a heterogeneously expressed transcription factor that plays a multifunctional role in many biological processes such as cell proliferation and differentiation. It is also associated with many types of cancer including the malignant lymphomas. There are two types of aggressive B-cell lymphoma, namely Burkitt lymphoma (BL) and a subgroup of diffuse large cell lymphoma (DLBCL), which both carry MYC translocations and overexpress MYC but both differ significantly in their clinical outcome. In DLBCL, MYC translocations are associated with an aggressive behavior and poor outcome, whereas MYC-positive BL show a superior outcome.

Methods

To shed light on this phenomenon, we investigated the different modes of actions of MYC in aggressive B-cell lymphoma cell lines subdivided into three groups: (i) MYC-positive BL, (ii) DLBCL with MYC translocation (DLBCLpos) and (iii) DLBCL without MYC translocation (DLBCLneg) for control. In order to identify genome-wide MYC-DNA binding sites a chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq) was performed. In addition, ChIP-Seq for H3K4me3 was used for determination of genomic regions accessible for transcriptional activity. These data were supplemented with gene expression data derived from RNA-Seq.

Results

Bioinformatics integration of all data sets revealed different MYC-binding patterns and transcriptional profiles in MYC-positive BL and DLBCL cell lines indicating different functional roles of MYC for gene regulation in aggressive B-cell lymphomas. Based on this multi-omics analysis we identified ADGRE5 (alias CD97) - a member of the EGF-TM7 subfamily of adhesion G protein-coupled receptors - as a MYC target gene, which is specifically expressed in BL but not in DLBCL regardless of MYC translocation.

Conclusion

Our study describes a diverse genome-wide MYC-DNA binding pattern in BL and DLBCL cell lines with and without MYC translocations. Furthermore, we identified ADREG5 as a MYC target gene able to discriminate between BL and DLBCL irrespectively of the presence of MYC breaks in DLBCL. Since ADGRE5 plays an important role in tumor cell formation, metastasis and invasion, it might also be instrumental to better understand the different pathobiology of BL and DLBCL and help to explain discrepant clinical characteristics of BL and DLBCL.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5537-0) contains supplementary material, which is available to authorized users.

Integrated MicroRNA-mRNA Analysis Reveals miR-204 Inhibits Cell Proliferation in Gastric Cancer by Targeting CKS1B, CXCL1 and GPRC5A

Gastric cancer (GC) is the second most frequent cause of cancer-related deaths worldwide. MicroRNAs are single-stranded RNA molecules of 21–23 nucleotides that regulate target gene expression through specific base-pairing interactions between miRNA and untranslated regions of targeted mRNAs. In this study, we generated a multistep approach for the integrated analysis of miRNA and mRNA expression. First, both miRNA and mRNA expression profiling datasets in gastric cancer from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) identified 79 and 1042 differentially expressed miRNAs and mRNAs, respectively, in gastric cancer. Second, inverse correlations between miRNA and mRNA expression levels identified 3206 miRNA–mRNA pairs combined with 79 dysregulated miRNAs and their 774 target mRNAs predicted by three prediction tools, miRanda, PITA, and RNAhybrid. Additionally, miR-204, which was found to be down-regulated in gastric cancer, was ectopically over-expressed in the AGS gastric cancer cell line and all down-regulated targets were identified by RNA sequencing (RNA-seq) analysis. Over-expression of miR-204 reduced the gastric cancer cell proliferation and suppressed the expression of three targets which were validated by qRT-PCR and luciferase assays. For the first time, we identified that CKS1B, CXCL1, and GPRC5A are putative targets of miR-204 and elucidated that miR-204 acted as potential tumor suppressor and, therefore, are useful as a promising therapeutic target for gastric cancer.

Expression and prognostic value of soluble CD97 and its ligand CD55 in intrahepatic cholangiocarcinoma

The incidence rate of intrahepatic cholangiocarcinoma is rising, and treatment options are limited. Therefore, new biological markers of intrahepatic cholangiocarcinoma are needed. Immunohistochemistry and enzyme-linked immunosorbent assay were applied to analyze the expressions of CD97, CD55, and soluble CD97 in 71 patients with intrahepatic cholangiocarcinoma and 10 patients with hepatolithiasis. CD97 and CD55 were not expressed in hepatolithiatic tissues, but positive expression was observed in 76.1% (54/71) and 70.4% (50/71) of intrahepatic cholangiocarcinoma patients. The univariate analyses indicated that the positive expressions of CD97 and CD55 were related to short intrahepatic cholangiocarcinoma survival of patients (both p = 0.001). Furthermore, CD97 and CD55 expressions and biliary soluble CD97 levels were significantly associated with histological grade (p = 0.004, 0.002, and 0.012, respectively), lymph node metastases (p = 0.020, 0.038, and 0.001, respectively), and venous invasion (p = 0.003, 0.002, and 0.001, respectively). The multivariate analyses indicated that lymph node metastases (hazard ratio: 2.407, p = 0.003), positive CD55 expression (hazard ratio: 4.096, p = 0.003), and biliary soluble CD97 levels (hazard ratio: 2.434, p = 0.002) were independent risk factors for the intrahepatic cholangiocarcinoma survival. The receiver operating characteristic (ROC) curve analysis indicated that when the cutoff values of biliary soluble CD97 were 1.15 U/mL, the diagnostic value for predicting lymph node metastasis had a sensitivity of 87.5% and a specificity of 51.3%. For intrahepatic cholangiocarcinoma patient death within 60 months at a cutoff value of 0.940 U/mL, the diagnostic value sensitivity was 89.3% and the specificity was 93.3%. Biliary soluble CD97 may be a new biological marker for early diagnosis, prediction of lymph node metastasis and poor prognosis, and discovery of a therapeutic target.

Comparative protein profiling of B16 mouse melanoma cells susceptible and non-susceptible to alphavirus infection: Effect of the tumor microenvironment

Alphavirus vectors are promising tools for cancer treatment. However, relevant entry mechanisms and interactions with host cells are still not clearly understood. The first step toward a more effective therapy is the identification of novel intracellular alterations that could be associated with cancer aggressiveness and could affect the therapeutic potential of these vectors. In this study, we observed that alphaviruses efficiently infected B16 mouse melanoma tumors/tumor cells in vivo, whereas their transduction efficiency in B16 cells under in vitro conditions was blocked. Therefore, we further aimed to understand the mechanisms pertaining to the differential transduction efficacy of alphaviruses in B16 tumor cells under varying growth conditions. We hypothesized that the tumor microenvironment might alter gene expression in B16 cells, leading to an up-regulation of the expression of virus-binding receptors or factors associated with virus entry and replication. To test our hypothesis, we performed a proteomics analysis of B16 cells cultured in vitro and of B16 cells isolated from tumors, and we identified 277 differentially regulated proteins. A further in-depth analysis to identify the biological and molecular functions of the detected proteins revealed a set of candidate genes that could affect virus infectivity. Importantly, we observed a decrease in the expression of interferon α (IFN-α) in tumor-isolated cells that resulted in the suppression of several IFN-regulated genes, thereby abrogating host cell antiviral defense. Additionally, differences in the expression of genes that regulate cytoskeletal organization caused significant alterations in cell membrane elasticity. Taken together, our findings demonstrated favorable intracellular conditions for alphavirus transduction/replication that occurred during tumor transformation. These results pave the way for optimizing the development of strategies for the application of alphaviral vectors as a potent cancer therapy.

Immunohistochemical Expression and Prognostic Significance of CD97 and its Ligand DAF in Human Cervical Squamous Cell Carcinoma

Accumulating evidences had demonstrated that the CD97, a member of the epidermal growth factor 7-transmembrane family, and its cellular ligand decay accelerating factor (DAF) both play important roles in tumor dedifferentiation, migration, invasiveness, and metastasis. However, the roles of CD97 and DAF in human cervical squamous cell carcinoma (CSCC) have not been investigated. The purpose of this study was to observe the expression profile of CD97 and DAF in CSCC and evaluate their clinical significance. Immunohistochemistry was used to investigate the expression of CD97 and DAF proteins in 97 patients with CSCC and 53 patients with cervical intraepithelial neoplasia, a precursor lesion of CSCC. CD97 and DAF were absent or only weakly expressed in the normal epithelium of the cervix but were present in 83.5% (81/97) and 90.7% (88/97) of CSCC samples, respectively. Overexpression of CD97 was significantly associated with a high International Federation of Gynecology and Obstetrics stage (P=0.010) and lymph node metastasis (P=0.026). The majority of CSCCs, irrespective of staging/grading classification, displayed strong DAF immunostaining. Kaplan-Meier survival analysis revealed that overexpression of CD97 was associated with a worse prognosis. Multivariate analyses showed that the International Federation of Gynecology and Obstetrics stage (P=0.000), lymph node metastasis (P=0.004), and CD97 expression (P=0.040) were independent risk factors for overall survival. The present study suggested that the expressions of CD97 and DAF were both upregulated in CSCC. The expression level of CD97 in CSCC was associated with the severity of the tumor. Furthermore, CD97 might be an independent poor prognostic factor for CSCC patients.

CD97 promotion of gastric carcinoma lymphatic metastasis is exosome dependent

BACKGROUND

CD97 knockdown impairs the metastatic capacity of SGC-7901 gastric cancer cells. However, the role of CD97 in the distant lymphatic premetastatic niche formation of gastric cancer remains unknown.

METHODS

Exosomes and the soluble fraction were isolated from SGC-L (an SGC-7901-cell-derived highly lymphatic metastatic cell line) and CD97-knockdown (SGC-L/CD97-kd) cells, and were co-cultured with gastric cancer cells. The metastatic capacity of the two cell lines was evaluated in vitro and in a footpad lymph node metastasis mouse model. Premetastatic-niche-formation-related proteins were examined immunohistochemically.

RESULTS

CD97 expression was ninefold higher in SGC-L cells than in SGC-7901 cells. In vitro, exosomes or conditioned medium from the SGC-L cells enhanced cell proliferation (20 % increase) and invasion (30 % increase) as compared with that from SGC-L/CD97-kd cells (p < 0.01). Intrafootpad injections of SGC-L, but not SGC-L/CD97-kd exosomes or conditioned medium, strongly promoted SGC-L and SGC-L/CD97-kd cell accumulation in the draining lymph nodes (p < 0.01) and increased CD55, CD44v6, α5β1, CD31, epithelial cell adhesion molecule, and CD151 expression. Although the SGC-L/CD97-kd exosomes alone were insufficient for promotion of metastasis, they were partly aided by the SGC-L-cell-derived soluble fraction.

CONCLUSIONS

The CD97 small isoform promotes SGC-L cell lymphatic metastasis exosome dependently, and aided by the soluble fraction, the exosome-dependent CD97 plays a pivotal role in premetastatic niche formation.

CD97 promotes gastric cancer cell proliferation and invasion through exosome-mediated MAPK signaling pathway

AIM: To investigate the mechanism underlying the promoting role of CD97 in gastric cancer cell proliferation and invasion.

METHODS: Two types of exosomes released by gastric cancer cells with high (SGC/wt) or low (SGC/kd) CD97 expression were isolated by ultracentrifugation and identified by electron microscopy and western blot analysis. The influences of the two exosomes on gastric cancer cell proliferation and invasion were investigated by proliferation and Matrigel invasion assays. Exosomal miRNAs were subsequently isolated from the two samples and their miRNA profiles were compared via microarray assay analysis. Reverse transcription-quantitative real-time polymerase chain reaction was used to validate the microarray assay. Target genes of the differently expressed microRNAs were predicted based on five independent algorithms and were then subjected to gene oncology enrichment and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis. After identifying the pathway that was the most likely altered, tumor cells were treated with the two exosomes at different concentrations, and the pathway activation was identified through western blot analysis.

RESULTS: Exosomes isolated from SGC/wt cells significantly promoted tumor cell proliferation in a dose-dependent manner in vitro. SGC/wt exosomes also significantly elevated the invasiveness of both SGC/wt (129.67 ± 8.327 vs 76.00 ± 5.292, P < 0.001) and SGC/kd (114.52 ± 9.814 vs 45.73 ± 4.835, P < 0.001) cells as compared to the exosomes released by SGC/kd cells. Microarray assay of the two exosomes revealed that 62 miRNAs were differently regulated with a signal intensity of > 500 and a false discovery rate < 0.05. The following KEGG analysis defined the MAPK signaling pathway as the most likely candidate pathway that regulated tumor cell proliferation and invasion. Through western blot analysis, significant up-regulations of phosphorylated MAPKs, including extracellular signal-regulated kinase, Jun NH2-terminal kinase, and p38 mitogen-activated protein kinase, were detected in a dose-dependent manner in the SGC/wt exosomes treated groups, confirming activation of the MAPK signaling pathway stimulated by SGC/wt exosomes.

CONCLUSION: CD97 promotes gastric cancer cell proliferation and invasion in vitro through exosome-mediated MAPK signaling pathway, and exosomal miRNAs are probably involved in activation of the CD97-associated pathway.

Proportional upregulation of CD97 isoforms in glioblastoma and glioblastoma-derived brain tumor initiating cells

CD97 is a novel glioma antigen that confers an invasive phenotype and poor survival in patients with glioblastoma (GBM), the most aggressive primary malignant brain tumor. The short isoform of CD97, known as EGF(1,2,5), has been shown to promote invasion and metastasis, but its role in gliomas and GBM-derived brain tumor initiating cells (BTICs) has not been studied. We sought to characterize CD97 expression among gliomas and identify the specific isoforms expressed. The short isoform of CD97 was identified in GBM and GBM-derived BTICs, but not low grade or anaplastic astrocytomas. All samples expressing the EGF(1,2,5) isoform were also found to express the EGF(1,2,3,5) isoform. These isoforms are believed to possess similar ligand binding patterns and interact with chondroitin sulfate, a component of the extracellular matrix, and the integrin α5β1. Using data acquired from the Cancer Genome Atlas (TCGA), we show that CD97 is upregulated among the classical and mesenchymal subtypes of GBM and significantly decreased among IDH1 mutant GBMs. Given its proven roles in tumor invasion, expression among aggressive genetic subtypes of GBM, and association with overall survival, CD97 is an attractive therapeutic target for patients with GBM.

Expression and prognostic value of CD97 and its ligand CD55 in pancreatic cancer

CD97 is a member of the epidermal growth factor-seven transmembrane family. It affects tumor aggressiveness by binding its cellular ligand CD55 and exhibits adhesive properties. Previous studies have shown that CD97 and CD55 are involved in the dedifferentiation, migration, invasiveness and metastasis of tumors. However, little is known regarding the roles of CD97 and CD55 in pancreatic cancer. In this study, immunohistochemistry was used to analyze CD97 and CD55 protein expression in samples obtained from 37 pancreatic cancer patients. CD97 and CD55 were absent or only weakly expressed in the normal pancreatic tissues but strongly expressed in pancreatic cancer tissues (P<0.05), particularly in tissues with lymph node involvement, metastasis or vascular invasion (P<0.05). Notably, CD97 and CD55 were expressed consistently in pancreatic cancer tissues (r²=0.5422; P<0.05). In addition, CD97 and CD55 expression levels were found to significantly correlate with tumor aggressiveness (P<0.01). Multivariate analyses revealed that CD97 and CD55 expression levels were closely associated with prognosis (P<0.05). Taken together, these results indicated that CD97 and its ligand CD55 are upregulated in pancreatic cancers and are closely associated with lymph node involvement, metastasis and vascular invasion. Thus, analysis of both CD97 and CD55 expression may present potential prognostic value for pancreatic cancer.

CD97 is a multifunctional leukocyte receptor with distinct roles in human cancers (Review)

G-protein coupled receptors (GPCRs) represent the most diverse and biologically ubiquitous protein receptors. The epidermal growth factor seven-span transmembrane (EGF-TM7) family consists of adhesion GPCRs with a diverse functional repertoire. CD97 is the most broadly expressed member with roles in cell adhesion, migration and regulation of intercellular junctions. CD97 is also expressed in a variety of human malignancies including those of the thyroid, stomach, colon and brain. CD97 confers an invasive phenotype and has been shown to correlate with tumor grade, lymph node invasion, metastatic spread and overall prognosis. More recently, CD97 was found to signal through Gα12/13, resulting in increased RHO-GTP levels. Proven roles in tumor invasion and signaling make CD97 an exciting novel therapeutic target. In this review, we will discuss the structure and function of this receptor, with a specific focus on its mechanistic significance in neoplastic diseases.

The invasion and metastasis promotion role of CD97 small isoform in gastric carcinoma

CD97 is over-expressed in the majority of gastric adenocarcinomas and is associated with its dedifferentiation and aggressiveness. Our previous results demonstrated that out of three CD97 isoforms tested, only the small one was able to promote increased invasiveness in vitro. Based on these data we further aimed to investigate the role of CD97 small isoform in gastric cancer progression in vivo by employing the cells with a stable CD97 small isoform knock-down and an orthotopic gastric cancer mouse model. We could demonstrate that the knock down of CD97/EGF1,2,5, led to a significant decrease in the number of cells penetrating the gelatin coated membrane as compared with control cells. In the gastric cancer mouse model, both the hypodermic and the orthotopic yielded tumor masses of the CD97/EGF1,2,5kd group and were significantly smaller than the control. Metastatic tumor cell number in early metastatic regional lymph nodes on post-operative day 42 was distinctly decreased in the CD97/EGF1,2,5kd group as compared with the SGC-NS group, and was accompanied with the downregulation of CD44, VEGFR, CD31 and CD97. We concluded in this study that CD97 small isoform not only supported gastric cancer local growth, but also promoted metastatic spread in orthotopically implanted mouse model suggesting involvement of the CD97 small isoform in the preparation of (pre)metastatic niche.

Immunohistochemical expression and prognostic value of CD97 and its ligand CD55 in primary gallbladder carcinoma

Background. CD97 as a member of the EGF-TM7 family with adhesive properties plays an important role in tumor aggressiveness by binding its cellular ligand CD55, which is a complement regulatory protein expressed by cells to protect them from bystander complement attack. Previous studies have shown that CD97 and CD55 both play important roles in tumor dedifferentiation, migration, invasiveness, and metastasis. The aim of this study was to investigate CD97 and CD55 expression in primary gallbladder carcinoma (GBC) and their prognostic significance. Methods. Immunohistochemistry was used to investigate the expression of CD97 and CD55 proteins in 138 patients with GBC. Results. CD97 and CD55 were absent or only weakly expressed in the normal epithelium of the gallbladder but in 69.6% (96/138) and 65.2% (90/138) of GBC, respectively, remarkably at the invasive front of the tumors. In addition, CD97 and CD55 expressions were both significantly associated with high histologic grade (both P = 0.009), advanced pathologic T stage (P = 0.01 and 0.009, resp.) and clinical stage (both P = 0.009), and positive venous/lymphatic invasion (both P = 0.009). Multivariate analyses showed that CD97 (hazard ratio, 3.236; P = 0.02) and CD55 (hazard ratio, 3.209; P = 0.02) expressions and clinical stage (hazard ratio, 3.918; P = 0.01) were independent risk factor for overall survival. Conclusion. Our results provide convincing evidence for the first time that the expressions of CD97 and CD55 are both upregulated in human GBC. The expression levels of CD97 and CD55 in GBC were associated with the severity of the tumor. Furthermore, CD97 and CD55 expressions were independent poor prognostic factors for overall survival in patients with GBC.

The impact of expressions of CD97 and its ligand CD55 at the invasion front on prognosis of rectal adenocarcinoma

BACKGROUND

Various evidence show that CD97 plays an important role in tumor differentiation, migration, invasiveness, and metastasis by binding its cellular ligand CD55. CD55 is a complement regulatory protein expressed by cells to protect them from bystander attack by complement, and it has been shown to be an indicator of poor prognostic in several cancers.

METHODS

CD97 and CD55 stains were detected in tumor tissues from 71 cases of rectal adenocarcinomas and their corresponding normal colorectal tissues by immunohistochemistry.

RESULTS

The expressions of CD97 and CD55 in rectal tumor tissues were significantly higher than those in normal colorectal tissues (P < 0.05, both). The patients with recurrence and/or metastasis had significantly higher expressions of CD97 at tumor cells and CD55 at stroma (67.8% [21/31] and 63.6% [21/33]) at the invasion front than those patients without recurrence and/or metastasis (25.0% [10/40] and 26.3% [10/38]). The expression of CD97 at tumor cell at the invasion front showed modest correlation with that of CD55 in the stroma at the invasion front(r = 0.392, P < 0.01). Univariate analysis revealed that lymph node metastasis (P = 0.001), stages II-IV (P = 0.026), and strong CD97 expression at tumor invasion front (P = 0.002) were shown to have a significant adverse impact on the postoperative survival rate. Moreover, lymph node metastasis (P = 0.037) and strong CD97 expression (P = 0.015) were associated with poor survival in a multivariate analysis.

CONCLUSIONS

Elevated expression of CD97 and its ligand CD55 at the invasion front correlate with tumor recurrence and metastasis, and CD95 may be a poor prognostic factor for rectal adenocarcinoma.

A voting approach to identify a small number of highly predictive genes using multiple classifiers

Background

Microarray gene expression profiling has provided extensive datasets that can describe characteristics of cancer patients. An important challenge for this type of data is the discovery of gene sets which can be used as the basis of developing a clinical predictor for cancer. It is desirable that such gene sets be compact, give accurate predictions across many classifiers, be biologically relevant and have good biological process coverage.

Results

By using a new type of multiple classifier voting approach, we have identified gene sets that can predict breast cancer prognosis accurately, for a range of classification algorithms. Unlike a wrapper approach, our method is not specialised towards a single classification technique. Experimental analysis demonstrates higher prediction accuracies for our sets of genes compared to previous work in the area. Moreover, our sets of genes are generally more compact than those previously proposed. Taking a biological viewpoint, from the literature, most of the genes in our sets are known to be strongly related to cancer.

Conclusion

We show that it is possible to obtain superior classification accuracy with our approach and obtain a compact gene set that is also biologically relevant and has good coverage of different biological processes.

Cancer stem cells as targets for cancer therapy: selected cancers as examples

It is becoming increasingly evident that cancer constitutes a group of diseases involving altered stem-cell maturation/differentiation and the disturbance of regenerative processes. The observed malignant transformation is merely a symptom of normal differentiation processes gone astray rather than the primary event. This review focuses on the role of cancer stem cells (CSCs) in three common but also relatively under-investigated cancers: head and neck, ovarian, and testicular cancer. For didactic purpose, the physiology of stem cells is first introduced using hematopoietic and mesenchymal stem cells as examples. This is followed by a discussion of the (possible) role of CSCs in head and neck, ovarian, and testicular cancer. Aside from basic information about the pathophysiology of these cancers, current research results focused on the discovery of molecular markers specific to these cancers are also discussed. The last part of the review is largely dedicated to signaling pathways active within various normal and CSC types (e.g. Nanog, Nestin, Notch1, Notch2, Oct3 and 4, Wnt). Different elements of these pathways are also discussed in the context of therapeutic opportunities for the development of targeted therapies aimed at CSCs. Finally, alternative targeted anticancer therapies arising from recently identified molecules with cancer-(semi-)selective capabilities (e.g. apoptin, Brevinin-2R) are considered.

Decay-accelerating factor (CD55): a versatile acting molecule in human malignancies

The decay-accelerating factor (DAF, CD55) physiologically serves as an inhibitor of the complement system. Moreover, DAF is broadly expressed in malignant tumors. Here, DAF seems to dispose of several different functions reaching far beyond its immunological role, e.g., promotion of tumorigenesis, decrease of complement mediated tumor cell lysis, autocrine loops for cell rescue and evasion of apoptosis, neoangiogenesis, invasiveness, cell motility, and metastasis via oncogenic tyrosine kinase pathway activation, and specific seven-span transmembrane receptors (CD97) binding. Furthermore, DAF has already been included in diagnostic or therapeutic studies. Thereby, studies applying monoclonal anti-DAF antibodies and anti-DAF vaccination for a targeted therapy have been enrolled recently.

Proteome profile of the MCF7 cancer cell line: a mass spectrometric evaluation

The development of novel proteomic technologies that will enable the discovery of disease specific biomarkers is essential in the clinical setting to facilitate early diagnosis and increase survivability rates. We are reporting a shotgun two-dimensional (2D) strong cationic exchange/reversed-phase liquid chromatography/electrospray ionization tandem mass spectrometry (SCX/RPLC/ESI-MS/MS) protocol for the analysis of proteomic constituents in cancerous cells. The MCF7 breast cancer cell line was chosen as a model system. A series of optimization steps were performed to improve the LC/MS experimental setup, sample preparation, data acquisition and database search protocols, and a data filtering strategy was developed to enable confident identification of a large number of proteins and potential biomarkers. This research has resulted in the identification of >2000 proteins using multiple filtering and p-value sorting. Approximately 1600-1900 proteins had p < 0.001, and, of these, approximately 60% were matched by >or=2 unique peptides. Alternatively, >99% of the proteins identified by >or=2 unique peptides had p < 0.001. When searching the data against a reversed database of proteins, the rate of false positive identifications was 0.1% at the peptide level and 0.4% at the protein level. The typical reproducibility in detecting overlapping proteins across replicate runs exceeded 90% for proteins matched by >or=2 unique peptides. According to their biological function, approximately 200 proteins were involved in cancer-relevant cellular processes, and over 25 proteins were previously described in the literature as putative cancer biomarkers, as they were found to be differentially expressed between normal and cancerous cell states. Among these, biomarkers such PCNA, cathepsin D, E-cadherin, 14-3-3-sigma, antigen Ki-67, TP53RK, and calreticulin were identified. These data were generated by subjecting to MS analysis approximately 42 microg of sample, analyzing 16 SCX peptide fractions, and interpreting approximately 55,000 MS2 spectra. Total MS time required for analysis was 40 h.